[Cell wall components in Staphylococcus aureus with double resistance to gramicidin S and actinomycin D].

Cell walls of Staphylococcus aureus R9/80 resistant to gramicidin S and actinomycin D were investigated. The strain was isolated after passages of a previously isolated strain of S. aureus with resistance to gramicidin and definite changes in the cell walls, a medium with increasing concentrations of actinomycin being used for the passages.

[Impact of exogenous glycine on actinomycin D resistance of Staphylococcus aureus strain adapted to the antibiotic].

The impact of glycine, added to the cultivation medium, on resistance of Staphylococcus aureus strains to actinomycin D and gramicidin S was studied. The antibiotic resistant strains were isolated after cultivation of the susceptible S. aureus strain 209P on media with increasing concentrations of actinomycin or gramicidin.

[The study of Staphylococcus aureus strain resistant to actinomycin D].

Staphylococcus aureus strains, resistant to actinomycin D (AMD) and to gramicidin S (GS) were selected by S. aureus 209P passing on the media containing the above mentioned drugs. Strain R80 resistant to AMD and strain R9 resistant to GS and AMD and described before didn't perform enzyme inactivation of AMD.

[The capacity of the mycelia of Streptomyces chrysomallus variants to bind exogenous actinomycin D and the synthesis by these variants of macrotetralides].

Streptomyces chrysomallus is known as an organism producing macrotetrolides (MTL) and actinomycin C. The dynamics of the MTL biosynthesis by some variants of S. chrysomallus in the process of their growth in liquid media was studied.

[Interaction of actinomycin D with suspended mycelium of streptomyces].

Binding of exogenous actinomycin D (AMD) by washed mycelium of streptomycetes i.e. variants of Streptomyces chrysomallus producing and not producing actinomycins and Streptomyces lividans not synthesizing the antibiotics was studied.

[The effect of millimeter-band radiation of nonthermal intensity on sensitivity of Staphylococcus to various antibiotics].

The affect of preliminary irradiation of staphylococcus culture by electromagnetic radiation of extremely high frequency (42, 54, 66 + 78 GHz) of nonthermal intensity on the bacteria growth on the media containing various antibiotics is studied. The reliable change in bacteria sensitivity toward 5 antibiotics, mainly having membranotropic properties is observed in the experiments using 14 antibiotics with various mechanisms of action. It has been established that in the presence of subbactericide concentrations of active antibiotics the irradiation could result in both further suppression of bacteria growth and its stimulation.

[Absorption of various actinomycins by Staphylococcus aureus cells].

The absorption of actinomycin D by the cell suspension of Staphylococcus aureus via diffusion linearly depended on the antibiotic concentration in the suspension within the ranges of 2 to 15 micrograms/ml. The absorption of active actinomycins C2, C3 and Au6 was the same as that of actinomycin D. The Staphylococcus intact membranes limited the inlet of the actinomycins to the cells since the membranotropic substances such as gramicidin S and its derivatives and thyrocidin increased their absorption by 30-70 per cent.

[Actinomycin D resistance of gramicidin-resistant strains of Staphylococcus].

Factors defining actinomycin D resistance in Staphylococcus aureus resistant to gramicidin S were investigated. The results of the thin layer chromatography, high-voltage electrophoresis and bioautography showed that the resistant cells did not inactivate actinomycin D by the hydrolysis of the lactone bond in the antibiotic molecule. The estimation of the cell ability to bind actinomycin D revealed that the antibiotic binding to the resistant cells was lower by 70-75 per cent as compared to the cells of the susceptible strains.

[Isolation and investigation of Staphylococcus aureus strains resistant to the membrane active antibiotic, gramicidin S].

Strains of Staphylococcus aureus 209P growing in the presence of 20 micrograms/ml of gramicidin S were isolated after the successive subculture on a liquid medium with increasing concentrations of the antibiotic. The resistance was stable and preserved after the subculture on media not containing the antibiotic. The development of the resistance to gramicidin S did not lower the cell sensitivity to a large number of antibiotics known as inhibitors of the cell wall synthesis, protein synthesis and RNA-polymerase reaction.

[Comparative study on the activity of some enzyme systems in cells of gramicidin S sensitive and resistant strains of Staphylococcus aureus].

Polarographic determination of the rate of endogenic respiration of the cells of Staphylococcus aureus 209P showed that the respiration activity of the cells of the strain resistant to 20 micrograms/ml of gramicidin S was 20 to 30 per cent lower than that of the sensitive strain. The rate of oxygen consumption in oxidation of NADH by the membrane preparations of the resistant cells was also 25 to 30 per cent lower. By comparison with the initial sensitive strain the activity of endogenic DPI-reductases of the intact cells and NADH-dehydrogenases of the membranes of the resistant strain was also lower.

[Metabolism of alpha-ketoacids in erythromycin biosynthesis in various strains of Saccharopolyspora erythraea].

The absence of pyruvate and insignificant levels of alpha-keto-glutarate in the mycelium during the fermentation cycle were characteristic of a highly active erythromycin-producing strain of Saccharopolyspora erythraea. Alpha-keto-glutarate partially excreted to the fermentoffon broth. The activity of pyruvate decarboxylase and alpha-keto-glutarate decarboxylase was detected in the cells during the entire period of the cultivation.

[Joint culturing of Streptococcus lactis, strain MGU with Proteus vulgaris and Bacillus mesentericus].

Nisin synthesis by Streptococcus lactis, strain MGU, grown as a combined culture together with Proteus vulgaris and Bacillus mesentericus under stationary conditions or with stirring does not depend on the quantity of inoculated associated cells. Nisin synthesis in the combined culture drops down by 10-20% at the initial pH 7.5 of the growth medium which is unfavourable for S.

[Nisin sorption and desorption on different silica adsorbents].

Nisin sorption on some silica adsorbents in columns was studied. Silica gels, silochromes and sintered glass with various pore diameters, various specific surfaces, etc. were tested.

[Use of adsorbents for optimizing the process of isolating nisin from the culture broth].

The results of the study on optimization of the process of nisin isolation from the cultural liquid are presented. Different adsorbents, streptococcal cells, medium solid particles (biomass fermentalysates) and silica gel, were used for antibiotic adsorption.

[Nisin adsorption on silica adsorbents].

It has been shown that silica adsorbents can be used for adsorption of nizin from solutions obtained after centrifugation of the fermentation broth. The optimal structure of the adsorbent pores has been determined. Silica with pores 50 to 75 nm in size provided the highest adsorption rates.

[Nisin inactivation in a culture of the producer Streptococcus lactis strain MGU].

The intensive biosynthesis of nizin on the glucose-yeast medium is observed during the logarithmic and early lag phases of the staphylococcal growth. The ratio of nizin in the fermentation broth (free nazin) and that bound with the cells depended on pH of the medium. When pH was maintained at 6.

[Conditions for nisin adsorption by Streptococcus lactis cells].

Some conditions for absorption of nisin, a polypeptide antibiotic by the cells of Str. lactis were studied. The amounts of nisin adsorbed by the cells depended on the culture age: at the late stationary phase the adsorption level was 2 times higher than that at the logarithmic phase.

[Adsorption of the antibiotic, nisin, to Streptococcus lactis cells].

Nizin is produced by Str. lactis, strain MSU. During biosynthesis it is excreted into the fermentation broth and gradually adsorbed on the organism cells.

[Method of determining the concentration of the antibiotic nisin].

To accelerate determination of nizin concentrations by the agar-diffusion method it is suggested that Twin-80 be added to the agar. For making the media composition more simple, agarized phosphate buffer, pH 5.0, or agarized water, pH 7.

[Dynamics of nisin accumulation in a culture of Streptococcus lactis].

The dynamics of nisine accumulation by its producer Streptococcus lactis, str. MSU was studied. In the course of the producer cultivation on the liquid nutrient medium there was a correlation between total, cellular and filtrate nysine.

[Influence of pH on nisin production by Streptococcus lactis cultures].

The pH effect on the nisine biosynthesis during the cultivation of Streptococcus lactis was studied at pH 5,8 6,7 and 7,2. The pH maintenance at the specified level did not stimulate the growth of Str. lactis, did not increase the total yield of nisine and did not produce a significant effect on the level or cellular nisine.

[Effect of the initial pH value of the medium on the growth of Streptococcus lactis and the biosynthesis of nisin].

The effect of the initial pH value of the medium within 4.0 to 6.6 on the growth of Str.